Armature-slot insulation and method of making the same



March 18 1924.

L. T. FREDERICK ARMATURE SLOT INSULATION AND METHOD OF MAKING THE SAME Filed Jan. 8,

Y INVENTOR Law's I Frederic/r WITNESSES:

TTo RNEY Patented Mar. 18, 1924.

UNITED STATES PATENT OFFICE.

LOUIS '1. FREDERICK, OF WILKINSBURG,

PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A. CORPORATION OF PENNSYL- VAN'IA,

Application flled January 8, 1919. Serial No. 270,143.

To all whom it may concern:

a citizen of the United States, and a'resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Armature-Slot Insulations and Methods of Making the Same, of which the following is a specification.

My invention relates and more for insulating armature slots of dynamo electric machines, and it has for its primary object the. provision of insulating material to electric insulation which may be employed as insulation for armature slots in such manner as to realize a saving of material heretofore.

One object of my invention is the provision of insulating material, of the character above mentioned, by employing a flexible material im regnated with-a plurality of insulating a hesives and cementing thereto a reinforcin material which shall lend greater rigidity of form to the composite insulation thus provided.

Another object of my ,invention is to provide an insulating material especially adapted for insulating armature slots which may be more easily and eflicientlyapplied t0 the armature and-to thus accomplish a material saving of labor.

With these and other objects in view, my invention will be more fully described, illustratedin the drawings, inthe several views of which corresponding numerals indicate like parts, and then particularly pointed out in theclaims.

In the drawings, Fig. 1 is a diagrammatic view of an apparatus which may be utilized in preparing insulating material in accord ance Withmy invention; Fig. 2 is a transverse, sectional view of a shapedstrip of insulating material which is in readiness to be applied to an armature slot; Fig.3 is an end view of a portion of an armature core showing an insulated and partially filled slot, and Fig. 4 is a view, similar to Fig. 3,

particularly to material suitable over methods employed 7 and passed over a roll but showing a completely filled and insulated slot.

In practising my invention, I may repare insulating material by selecting a exible material, such as cloth, and impregnating it with a plurality of insulating adhesives, one of which is subsequently thoroughly dried while the other is partially dried. A cloth, treated in this manner, may then have a layer of reinforcing material, such as paper, which possesses a greater rigidity of form, fastened to it by the binding action of the semi-dried adhesive applied to the cloth.

'In insulating an armature slot with material prepared in accordance with my invention, the layers of fibrous material may be cut into sheets of suitable size and then shaped to substantially conform to the slots to be insulated. The formed strips may then be disposed within the armature slots and the coils positioned therein in the usual manner.

In order to illustrate the method of preparing insulating material in accordance such material to be led over an idler roll 3 into a vat or tank 4: containing a body of drying adhesive 5, such as an oil varnish. The cloth 2 is led through the adhesive 5 under a guide roll 6 an into a drying tower '7 which has suitable dividing partitions 8.

The cloth 2 is drawn into the drying tower 9 and emerges therefrom thoroughly dried, after which it is led to another tank or vat 10 containing another 1 adhesive 11 of greater viscosity than the ad hesive 5. The maternal passes through the adhesive 11, under a roll 12, and is again directed into the drying tower and over another uide roll 13 and emerges from the tower with the adhesive last applied in a partially dried state on account of the adhesive being less easily dried than thefirsta plied varnish. The adhesive 11, last apg'ed to the cloth, is, preferably, a slowrying liquid, such as an asphalt-gum varnish. The cloth, upon-emerging from the tower, after the second application of adhesive, is led under an idler roll 14 to a collecting roll 15. A roll 16 may be provided, carrying a suitable quantity of material 17 of greater rigidity than cloth, such as paper, and thepaper may be supplied to the roll 15 along with the treated cloth 2. The adhesive, last applied to the cloth, being in a partially wet state, cements the paper to the cloth as they are rolled simultaneously upon the collecting roll. Waxed paper may be interposed between the layers of material upon the roll 15.

A roll of material, prepared as above described, ma be out into sheets of suitable width and isposed in dies in order to shape the sheets to conform substantially to the shape of the walls of the armature slots to be insulated. A strip thus formed is shown in Fig. 2 in which the paper 17 constitutes the exterior and the treated cloth 2 the interior of the composite body. Since ture slot by merely slightly compressing the sides of the strip and by sliding it into place in the slot after which the coils, .to be carried by the slot, may be. positioned therein.

In the case of a slot WhlCh is to carry one side of each of two coils, as is shown in Fig. 3, the slot may be insulated by placing the stri cloth 2 and the paper 17, within the slot 18 and one of the coils 19 may then be disposed within the slot, after which asubstantiallystraight strip 20 of insulating material, e'mbodymg my invention, may be placed on the coil. The slot is then in readiness to receive one side of a second coil 21, which may be positioned therein and another wedge of insulating material 22 maybe disposed onthe coil 21 to substantially close the slot.

Insulating material prepared in accord-l ance with my invention is 'sufiiciently fleziible, when appliedto a slot, to allow for slight irregularities in the surface of the coils contained therein and to insure close adhesion to the coils and thorough insulation of them from the armature-core. Paper employed to reinforce the treated cloth is preferably so disposed as to engage the walls of the armature slot to facilitate disposing the several strips in place by exposing an untreated surface to sliding contact withthe walls. The cloth also insures eflicient insuof insulating material, comprising the ance with my invention on account of the fact that, heretofore, armature slots have been insulated by employing a suitable woven material or cloth which necessitated providing a piece or strip of such width that the sides of the material might be held above the armature while the first coil was being disposed in lace. When the first coil was disposed in plitce, the material or cloth projecting above the armature slot was then cut oil and a second similar strip was disposedin the slot with its ends also projecting therefrom, and a second coil was then dis osed in the slot, after which the mate ria projecting above the armature, was cut off and a wedge was'driven home into the remaining space above the last coil. The employment of cloth in this manner resultedin a waste of sutlicient materialto insulate an armature slot with a composite insulation prepared in accordance with my invention. The non-reinfoncedcloth, having no rigidity of form, must be held in position while the coils are being ositioned in the armature slot as, if not so lield, a wrinkling or bunching of material sufiicient to prevent properly placing the coil would result. By my invention, an exact amount of insulating'material may be ositioned in the slot in readiness to receive t e coil or coils to be carried therein.

It is obvious that various methods of applying adhesives to cloth may be utilized 7 and a variety of adhesives may be employed to prepare insulating material in accordexcept such as are indicated in the appended claims. I claimis my invention:

1. A method of making composite insulating material that comprises'impregnating cloth with an adhesive, sub'ecting the treated material to heat to bar en the adhesive, subjecting the cloth to further treatment in a bath of another adhesive of. greater viscosity than the first, partially dryin the second adhesive on the cloth and app ying paper to one side of the treated cloth.

2. A method of making composite insulating material that comprises impregnating cloth with an oil varnish, subjecting the cloth to heat to harden the varnish, subjecting the cloth to further treatment in a bath of an asphalt-gum varnish, partially drying the second varnish on the cloth and applying a layer of paper to one side of the treat slots comprising a layer of cloth treated ed cloth. with a plurality of adhesives and a layer of 10 3. An insulating material for armature paper cemented thereto, both layers being slots comprising superimposed layers of of substantially U-shape in cross-section. 5 fibrous material of substantially U-shape in In testimony whereof, I have hereunto cross-section and one layer of which is imsubscribed my name this 21st day of Dec., pregnated with a hardened adhesive. 1918.

4. An insulating material for armature LGUIS T. FREDERICK, v 

